The present invention relates to an olefinic thermoplastic elastomer, a composition, a sheet made of either one of them, a laminated product and covering skin sheets for interior furnishings of automobile.
Heretofore, coverage skin sheets for internal furnishings, such as instrument panel, door trim and so on, were made principally of soft vinyl chloride resin. In recent years, however, it has become to use an olefinic thermoplastic elastomer for it, in view of the common demand for light-weight articles. For shaping the covering skin sheet for internal furnishings made of an olefinic thermoplastic elastomer so as to conform it to the furnishing, such as instrument panel or door trim, a vacuum forming, above all, male vacuum forming has now been in practical use. The male vacuum forming is carried out using a non-grained forming mold having perforations for evacuating the interface between the mold surface and the covering skin sheet inside face by placing the grained (namely, grains are formed on the covering skin outer face beforehand by embossing) covering skin sheet on the mold with its grained outer face being exposed to the exterior and pressing the skin sheet onto the mold face by evacuating the space beneath the skin sheet. Therefore, the patterns on the grained outer face of the covering skin sheet may be apt to undergo deformation. In particular, a covering skin sheet made of an olefinic thermoplastic elastomer may suffer from such deformation of the pattern upon a vacuum forming, especially upon the male vacuum forming, more easily as compared with that made of soft vinyl chloride resin, resulting in an inferior ability for retaining the grains, so that it has been requested to obviate this disadvantage.
An olefinic thermoplastic elastomer exhibiting an improved ability for retaining the grains has been disclosed in Japanese Patent Kokai Hei 6-71751 A, which is obtained by subjecting a mixture composed of an olefinic copolymer rubber having a Mooney viscosity at 100xc2x0 C. of 80-350, an oil-extensible olefinic copolymer rubber and an olefinic polymer to a partial cross linking.
This olefinic thermoplastic elastomer exhibits still an insufficient ability for retaining the grains, so that a further improvement is expected.
An object of the present invention is to solve the problems concomitant to the prior art mentioned above and to provide an olefinic thermoplastic elastomer as well as a composition comprising such olefinic thermoplastic elastomer, which are superior in the formability, heat resistance, mechanical properties, tensile characteristics, strain restorability and repulsive elasticity, together with superior ability for retaining grains when a grained sheet made therefrom is processed by vacuum forming, in particular by male vacuum forming.
Another object of the present invention is to provide a sheet, a laminated product and a covering skin sheet for interior furnishings in automobile made of the above olefinic thermoplastic elastomer or the elastomeric composition, which are superior in the ability for retaining the grains upon male vacuum forming thereof.
The present invention resides in the following olefinic thermoplastic elastomer, elastomeric composition and applications:
(1) An olefinic thermoplastic elastomer comprising an olefinic resin and an olefinic copolymer rubber and having a characteristic feature that it satisfies, when a grained sheet made of the said elatomer is subjected to a male vacuum forming at least at a point of sheet temperature within the range of 130-150xc2x0 C., the condition that the grain retention rate expressed by the proportion of the grain depth of the sheet retained after the male vacuum forming relative to the grain depth before the male vacuum forming represented by percent meets the relation defind by the following equation (1)
xe2x80x83% retention of grainxe2x89xa7100xe2x88x922.0xc3x97(Txe2x88x92120)xe2x80x83xe2x80x83(1)
in which T represents the sheet temperature upon the male vacuum forming.
(2) An olefinic thermoplastic elastomer obtained by subjecting a rubber composition comprising
(A) 10-60%, based on the total weight of the composition, of a propylene resin having a melt flow rate (according to ASTM D 1238-65T, determined at 230xc2x0 C. under a load of 2.16 kg) in the range from 0.1 to 3 g/10 min.,
(B) 37-87%, based on the total weight of the composition, of an ethylenic copolymer rubber made from ethylene, an xcex1-olefin having 3-20 carbon atoms and an optionally incorporated non-conjugated polyene and
(C) 3-30%, based on the total weight of the composition, of a polyethylene resin
xe2x80x83to a dynamic heat treatment in the presence of a cross linking agent.
(3) An olefinic thermoplastic elastomer, obtained by subjecting a rubber composition comprising
(A) 10-60%, based on the total weight of the composition, of a propylene resin having a melt flow rate (according to ASTM D 1238-65T, determined at 230xc2x0 C. under a load of 2.16 kg) in the range from 0.1 to 3 g/10 min.,
(B) 37-87%, based on the total weight of the composition, of an ethylenic copolymer rubber made from ethylene, an xcex1-olefin having 3-20 carbon atoms and an optionally incorporated non-conjugated polyene and
(C) 3-30%, based on the total weight of the composition, of a polyethylene resin
xe2x80x83to a dynamic heat treatment in the presence of a cross linking agent, wherein the said elastomer has a characteristic feature that it satisfies, when a grained sheet made of the said elatomer is subjected to a male vacuum forming at least at a point of sheet temperature within the range of 130-150xc2x0 C., the condition that the grain retention rate expressed by the proportion of the grain depth of the sheet retained after the male vacuum forming relative to the grain depth before the male vacuum forming represented by percent meets the relation defind by the following equation (1)
% retention of grainxe2x89xa7100xe2x88x922.0xc3x97(Txe2x88x92120)xe2x80x83xe2x80x83(1)
in which T represents the sheet temperature upon the male vacuum forming.
(4) The olefinic thermoplastic elastomer as defined in the above (2) or (3), wherein the polyethylene resin (C) has a density in the range from 0.880 to 0.940 g/cm3.
(5) The olefinic thermoplastic elastomer as defined in any one of the above (2) to (4), comprising further a softener (D) in a proportion in the range from 10 to 200 parts by weight per 100 parts by weight of the ethylenic copolymer resin (B).
(6) The olefinic thermoplastic elastomer as defined in any one of the above (1) to (5), wherein the gel content thereof is in the range from above 20 to below 97%, based on the weight of the olefinic thermoplastic elasomer.
(7) The olefinic thermoplastic elastomer as defined in any one of the above (1) to (6), to be used as the material of coverage skin sheet for interior furnishings of automobile.
(8) An olefinic thermoplastic elastomeric composition, comprising the olefinic thermoplastic elastomer as defined in any one of the above (1) to (7) and a crystalline polyolefin resin (E), wherein the proportion of the crystalline polyolefin resin (E) is in the range from 20 to 200 parts by weight per 100 parts by weight of the olefinic thermoplastic elastomer.
(9) The olefinic thermoplastic elastomeric composition as defined in the above (8), to be used as the material of coverage skin sheets for interior furnishings of automobile.
(10) A sheet made of the olefinic thermoplastic elastomer as defined in any one of the above (1) to (7) or of the olefinic thermoplastic elastomeric composition as defined in the above (8) or (9).
(11) A grained sheet made of the olefinic thermoplastic elastomer as defined in any one of the above (1) to (7) or of the olefinic thermoplastic elastomeric composition as defined in the above (8) or (9).
(12) A sheet comprising
a substrate made of the sheet as defined in the above (10) or (11) and, coated thereon,
a top coat made of a material selected from the group consisting of polyurethane resin, saturated polyester resin, acrylate resin, polyvinyl chloride resin and isocyanate resin.
(13) A laminated product comprising
an external layer of the sheet as defined in any one of the above (10) to (12) and
substrate layer made of a foamed polyolefin.
(14) Covering skin sheets for interior furnishings in automobile, comprised of the olefinic thermoplastic elastomer as defined in any one of the above (1) to (7), of the olefinic thermoplastic elastomeric composition as defined in the above (8) or (9), of the sheet as defined in any one of the above (10) to (12) or of the laminated product as defined in the above (13).